New types of communication services are being introduced at an increasing rate, driving the demand for higher data rates and communication capacity. With the advent of high-speed logic circuits, data communication equipment has overwhelmingly moved toward digital implementations. The progress of communication systems is in part due to performance increases and cost reductions of digital circuit technology. Advancements in digital communication systems have also been based on significant theoretical developments. For example, Shannon's establishment of the fundamental limits on the transmission rates in digital communications motivated the search for coding techniques to approach the capacity limit.
Data communication signals transmitted over noisy channels are susceptible to errors caused by the interference. Various methods have been developed to minimize the effect of interference on the transmitted data. Digital systems are generally more reliable in noisy communications environments. Error correction coding involves representing the data in such a way that errors may be corrected. Further, digital data can be encoded in such a way that introduces dependency among a large number of symbols, thus enabling the receiver to make a more accurate detection of the symbols. This technique is known as forward error correction or error control coding.
The two most commonly used types of forward error correction codes are block codes and convolutional codes. Block codes involve operations that depend on the current input message and are independent of previous encodings. In contrast, operation of a convolutional code involves output sequences that depend not only on the current input message, but also on a number of past message blocks. Recursion algorithms used in convolutional coding may include a number of recursive steps to achieve a desired level of accuracy. The recursive steps require additional processing time that slows down the communication processes. There exists a need in the communication industry for methods and systems to increase the speed of digital communications systems.